This relates to ultra-capacitor powered devices.
An ultra-capacitor based device typically uses a single capacitor or a series/parallel combination of several capacitors. When capacitors are connected in parallel, the effective capacitance increases, providing higher energy storage. Today, ultra-capacitors are limited to 2.7 Volts. Therefore, to increase their output voltage, capacitors are connected in series, which reduces their capacitance. However, since the stored energy is proportional to the square of the voltage, higher energy storage at higher voltages may result.
An ultra-capacitor is also known as a super capacitor, a super condenser, or an electric double-layer capacitor. They are distinguished from other capacitors because they have a separator between two plates, that effectively creates a double capacitor.